The present invention relates to a liquid-cooled heavy-duty resistor.
A liquid-cooled power resistor is known from European Patent No. EP 0,066,902 B1. This liquid-cooled power resistor consists of a cylindrical housing provided with two flanges. The housing is closed at its ends with a top cover plate and a bottom cover plate. The flanges are constructed in cuboid form so that their corners protrude past the cylinder and are used for connecting the cover plates with mounting screws. The closed housing is provided with two ports for the supply of deionized water, an inlet bore provided in a bottom connection and an outlet bore being provided in a top connection.
Four deflector plates are mounted in the interior of the housing. These deflector plates alternately leave one flow cross section each open on the left and on the right and are used for deflecting the deionized water. The deflector plates are provided with bores through which a serpentine resistor conductor is carried. The deflector plates therefore also function as holders for the resistor conductor. The upper cover plate and lower cover plate are each provided with a connecting pin and fixed in location by means of a nut. The ends of the resistor conductor are connected to these connecting pins.
In this embodiment of the liquid-cooled power resistor, the cylinder with the flanges consists of aluminum and the cover plates consist of polypropylene. The deionized water used as cooling liquid runs through the power resistor and is continuously conditioned in bypass mode.
Arranging the resistor conductor directly in the cooling liquid ensures effective and uniform heat removal, the heat capacity being relatively high. In spite of the serpentine-like or meander-shaped arrangement of the resistor conductor, unfortunately this liquid-cooled power resistor still has a high inductance. In addition, its resistance value is relatively high, for example 10.OMEGA. to 100.OMEGA..
From the German Patent Application No. DE 36 39 239 A 1, a liquid-cooled resistor is known which consists of a hollow body with a resistor carrier arranged in its interior space. Resistance wire is wound about the resistor carrier. The hollow body and the resistor body consist of insulating material and are spaced apart from one another by an intermediate space forming a cooling duct. The cooling duct is connected to a coolant inlet at the lower end of the hollow body and to a coolant outlet at the upper end of the hollow body. The resistor carrier consists of a rod-shaped body with radially arranged arms on which the resistance wire is bidirectionally wound. Each of the ends of the resistance wire are connected to an electrical terminal. A resistor liquid-cooled in this manner has low inductance and can remove high dissipated power. Unfortunately, such resistors disadvantageously have low insulating strength and the cooling liquid must not be electrically conductive. Since a thin wire is used as a resistor conductor, the resistance value of such a liquid-cooled resistor is very high.
Therefore, there is a need for a liquid-cooled heavy-duty resistor which can remove high dissipated power in a small space, has low inductance and exhibits a very low resistance value.